Geodetic Constraints on Steric Sea Level Rise: Using Earth Oblateness as a Metric for Land Ice Ablation
Recent sea level observations reported by the IPCC and other sources show a global rise of about 3mm/yr, since the advent of satellite altimetry in the early 1990's. Attribution of this rise has been controversial, with some studies indicating that it can be fully explained by thermal expansion while others have shown a net heat loss by the oceans in recent years. Here we examine the combination of radar altimetry with geodetic observations of the Earth's dynamic oblateness (J2), as a means of providing independent constraints on changes in the steric component of sea level rise. In this presentation we focus on global sea level rise and subsequent fall during the 1997-98 El Nino. Steric sea level rise computed by a number of recent studies fails to account for the global anomaly observed during this event, and nonsteric contributions implied by changes in snow and ground water storage derived from the LaD hydrological model, while producing sea level anomalies that are well-correlated with the altimeter data, also fail to reproduce the full amplitude of the global sea level change. By using SLR-derived J2 data, which also showed a large anomaly during the late 1990's, we derive independent constraints on latitudinal shifts in water mass substance and hence on changes in high-latitude land ice ablation, and use these constraints to evaluate the contribution of mass balance changes in polar ice sheets and sub-polar glaciers to the large sea level anomaly observed during the 1997-98 ENSO.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 1218 Mass balance (0762;
- 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762;
- 1225 Global change from geodesy (1222;